Setting up iMC784 for a proper PQ monitoring

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Transcript of Setting up iMC784 for a proper PQ monitoring

Page 1: Setting up iMC784 for a proper PQ monitoring
Page 2: Setting up iMC784 for a proper PQ monitoring

Understanding the need for a proper

PQ set-up

Connecting iMC784

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Power Quality Analysers represent one of the most advanced metering

equipment, which became an essential part of every modern utility, industrial

and even building installation. Power quality related issues are a disease of a

modern supply system and are mostly hard to locate. They are very often

confused with equipment malfunction. Lack of information about supplied

power quality can lead to unexplained production problems and malfunction or

even damage to equipment used in production process.

Conventional meters were not designed to detect such anomalies hence PQ

analysers were built. As every musical instrument need to be tuned so must be PQ

analyser properly set-up and positioned on a right place to perform its task.

Besides installation place it is also important to understand what kind of loads

are installed on monitored location and what are normal operation

consumption levels.

PQ analyser iMC784 can be connected to any voltage level by means of dedicated

CTs and VTs. Choosing proper secondary values is important to be able to detect

various events with higher amplitudes. iMC784 can accurately measure currents

up to 15A and phase voltages up to 600V, which gives margin on three times

nominal value for 5A / 230V and much more when secondary values are 1A nad

110V.

For proper PQ analysis it is advised that connection system is three-phase four-

wire in order to monitor all phases directly and to detecet anomalies that would

occur in any power line. When this is not possible iMC784 supports all other

standard connection systems.

“iMC784 PQ analyser is

normally set up by a

Setting & Monitoring

software MiQen.

MiQen is user friendly

and powerfull tool

comes free as a part of a

iMC784 PQ monitoring

package.”

The iMC784 can be part

of a complete system by

using the server SW -

MiSMART

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Installation usually requires access to the restricted places and during

installation power is usually cut off. Therefore any further post-installation

intervention is not wanted. Therefore in case of wrong connection or project

change it is possible to remotely change phase channels through communication

and setting software.

PQ analyser iMC784 is by default already set up for PQ monitoring on four wire,

low voltage 230V, 50Hz system. When it is installed in a different system, certain

parameters should be modified.

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Enabling PQ monitoring“Settings can be also

performed offline by

MiQen setting software

and uploaded as a

complete setting file

(*.msf f i le) or just

individual section (e.g.

communication, energy,

I/Os, Alarms, Recorders,

Power Quality...).“

“ N e u t r a l l i n e C T

transformation ratio

can be separately

defined since currents

t h a t a r e f l o w i n g

through neutral line

have usually lower

magnitude”

„ I f m o re i d e n t i c a l

analysers should be

installed, setting file can

be uploaded to all and

save overall installation

time.”

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Monitoring mode can be set to standard EN50160 or can be disabled.

Electro Energetic System can be set to one of the systems defined by

EN50160

Monitoring voltage connection corresponds to connection system

(three or four wire)

Operating supply voltage is always a secondary voltage of a VT. This is a

nominal voltage for PQ analysis. If connection system is three phase,

phase-to-phase voltage needs to entered

Nominal power frequency can be either 50 Hz or 60 Hz

Flicker calculation function is different for systems with 110V or 230V

nominal low voltage. For proper flicker evaluation this needs to be chosen

correctly

Monitoring period is defined by EN50160 as 1 week

Flagged deviation evaluation; in some cases certain variation or

anomaly in supplied power triggers also some other events (e.g. certain

harmonics can also trigger flicker). Instrument detects this collateral event

and marks it (assigns a flag). PQ recorder always stores all events. But for

PQ report, user can define weather to include all events or should it skip

flagged events, which contribute to worse overall PQ report.

All Monitored data is stored in internal flash memory and evaluated

within the instrument itself. Optionally it can also be sent into the

MiSMART system server for remore monitoring

Settings of individual PQ indices (frequency variations, voltage variations...) are

predefined according to EN50160 requirements. It is always possible to change

them. In this case, report will not be a EN50160 compliant report (notice within

report).

Beside voltage and frequency related variations and events, latest standard for

class A PQ analysers (IEC61000-4-30 Ed.3) also defines procedures for current

monitoring. iMC784 is built according to latest standard and enables monitoring

current related disturbances.

Described settings are required for PQ monitoring. Advanced operation of

iMC784 enables also PQ analysis with precise event detection and recording in

order to evaluate cause and origin of an event.

“Comparing voltage and

c u r r e n t r e l a t e d

d i s t u r b a n c e s h e l p s

distinguish between

disturbances coming

f rom the gr id and

disturbances generated

by installed equipment

(production processes,

generators…)”

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The iMC784 instrument can be configured to be part of a comprehensive PQ

monitoring system where instrument-evaluated data is sent into the MiSMART

system SW to transfer PQ data automatically (via autonomous push XML

communication) as well as on demand data (via FTP) from one or multiple

instruments.

“Viewing PQ data as an

aggregated table with

the MiSMART native web

client"

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Additional PQ record settings

This detailed analysis is a useful tool for preventing further occurrence of events

and proper network planning. For such analysis, it is crucial to define various

triggers and signal records that will help evaluate the cause, nature, duration and

area spread of the event.

Setting up triggers for various event detection is simple by using MiQen setting

software:

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For each event detection (trigger) it is possible to define various actions:

- Waveform records on chosen channels (4 current, 4 voltage and 8 digital)

- Disturbance record (RMS reading with half cycle resolution) on chosen

channel

- Send crosstrigger to up to eight other PQ analysers

Also important is data format of recorded signals so they can be imported,

visualized and analysed with various softwares. For this purpose iMC784

supports standard PQDiff and Comtrade data formats.

“Signal shape and RMS

values records can

consume vast amount

of internal memory if

n o t c o n f i g u r e d

correctly.”

Transient triggers can detect voltage and current impulsive and

oscillatory transients with 32 µs resolution. This type of triggers are used

for shortest duration time events detection.

PQ Event triggers are defined with PQ standards. PQ events, which are

already part of standard PQ monitoring and reporting can be assigned

here for more detailed analysis by recording signal shapes.

External triggers are used in larger systems or in combination with

other equipment (e.g. protection relays). PQ analyser sends Ethernet

trigger (cross trigger), when it detects event, to other PQ analysers in the

network in order to evaluate area spread of an event. This is possible by

simultaneous records of the same event on different places. Information

is not lost due to pre-trigger time and precisely synchronised internal

clock. Digital triggers are extension of triggering mechanism to triggers

detected by other equipment or process and sent to PQ analyser in a

form of a digital signal.

Combined triggers are used for selective triggering mechanism. This

function enables generation of triggers as a logical combination of other

triggers, digital signals and alarms. By masking certain trigger

conditions this function helps detect events more precisely.

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Waveform recorder is used for most detailed analysis of detected event

with up to 625 samples/cycle and up to 0.5 sec pre-trigger time.

Disturbance recorder is used for longer period transition event analysis

but with lower resolution. Half-cycle or one-cycle resolution and up to

30sec pre-trigger time.

PQ recorder is permanent recorder (when enabled) and records all PQ

related variation and events as described in EN50160 standard with

aggregation intervals as described in IEC61000-4-30 standard.

Fast trend recorders are user defined recorders of all measured

quantities, with down to 1 sec storage interval.